A Waymo employee reveals how the company is putting their self-driving cars to the test (GOOGL)

Stephanie Villegas is a Googler who studied art before going to work for the Google Car project, now Waymo.

She located unused real estate at a former US Air Force base in California to transform it into a massive proving ground for Waymo self-driving vehicles.

Castle is now a 91-acre site that Waymo uses to throw everything its engineers can think of to challenge Waymo's self-driving cars.

Editor's note: Business Insider had the chance to speak with two Waymo employees from different parts of the company to learn more about their work. What we discovered were some of the coolest jobs at Alphabet, Waymo's parent company. This is the first in the series.

Stephanie Villegas was taking a break at Google's campus when a weird-looking Toyota changed everything.

"I was in one of Google's famous micro-kitchens when a Prius with a spinning bucket on top pulled up outside," she recalls.

It was 2009, and what we now know as Waymo, formerly the self-driving Google Car project had just been started. "It was still pretty confidential," Villegas. In fact, it was so confidential that it even had a code name: "Chauffeur."

At the time, Villegas was working on what she described as an "indoor mapping" project for Google's X lab. But the goofy looking Prius would soon out the University of California, Berkeley fine-art graduate on a completely different and unexpected path.

It all began with a ride.

Villegas went to check out the Prius, which was headed toward an autocross course. The operator of the car said they needed "ballast" in the back seat. So she jumped in.

After a few minutes of what she described as "ripping around corners," her mind was made up. "If you guys are hiring," she said, "let me know."

The wrinkle was that Google Car drivers had to try out. "Challenge accepted!" Villegas said, and by 2011, she was an operations driver. At Berkeley, she had studied painting, and after graduating had worked in a gallery, then later at a trading firm and a clothing boutique — hardly an atypical early career meander for a young person who didn't pursue engineering.

But also proof that even at an engineer's paradise such as Google, the company makes room for people who can bring something outside the box to the 19-year-old tech colossus. For Villegas, the company now called Alphabet created the opportunity to work on a much bigger canvas than she could have imagined.

How Google found its Castle in California's Central Valley

The googlers on the self-driving car project had been improvising. According to Villegas, they spent about six months running scenario tests in the Google parking lot, and they used the nearby Shoreline Amphitheater lot when it was quiet.

Villegas described the opposite of a command-and-control management system. When the team decided to explore situations that might come up on public roads, she ordered some supplies from Amazon. Then the Google Car vehicle began to deal with the more mundane aspects of everyday driving.

If the car knocked over a trash can, the engineers got excited, Villegas recalled. "They'd say, 'This is awesome!'"

But the project was rapidly outgrowing the Shoreline Amphitheater, which was also spoken for when concert season arrived in the spring. So Villegas went on a hunt for real estate.

She found it at decommissioned US Air Force base in Merced County, 130 miles east of the Googleplex in California's vast Central Valley.

Castle AFB had been closed for over a decade when Villegas got a look at its 50 acres and dilapidated, leftover roadways. The Cold War ruin had a new lease on life.

In 2018, it's called Castle, and the Google Car project is called Waymo. As Waymo — which Morgan Stanley recently valued as a $175 billion company — prepares to launch commercially later this year, the site has grown to 91 acres.

Villegas is a Structured Testing Lead, spending her days designing inventive ways to stress out what Waymo calls its "driver," an orchestration of laser-radars, sensors, computers, and software that's racked up over eight million miles of autonomous operation in Waymo's decade of existence.

Villegas has access to all the powerful, high-tech resources Waymo can provide, but science fiction hasn't always been her modus operandi.

"When we expanded, it was a field of dirt," she said. "But we wanted a little neighborhood with a cul de sac and railroad tracks. I talked to civil engineers to see if it was possible. It was basically me with a pencil and a piece of paper."

How Castle helped Waymo become a $175-billion company

Villegas' working life now consists of fine-tuning her creation. In the beginning, Castle was rough — intentionally. Google left the potholes to test the durability of self-driving platform, such as the adorable Firefly podmobile. Roads weren't repaved and lines weren't repainted so that the pavement more closely resembled America's infamously beleaguered real-world infrastructure.

Comforts have crept in, however.

"We have an office there, as well as a local team, and all the test associates are from the area so they don't have to commute," Villegas said. "And we don't have to stand out in the Central Valley heat all day."

Although Villegas spent much of her time at Castle "back in the day," as she puts its, her average week finds her at the facility less frequently. Waymo biggest current challenge is adapting the various dynamics of the different vehicles the company has partnered with automakers — Fiat Chrysler, Jaguar — to use.

Waymo's CEO John Krafcik also isn't limiting the company's expansion to passenger cars. A logistics business means semi trucks. For that, Villegas said, the old Air Force base's taxiway comes in handy.

Villegas clearly pinches herself from time to time. That spinning-bucket Prius could be worth more than three General Motors. "The most thrilling thing was the day I rode in the vehicle on non-public roads with no one in he driver's seat," she said.